Cardboard boxes which are folded from a single cardboard piece are very common, and typically comprise a flat cardboard blank, which is folded together to define a rectangular, tubular body having four walls, with each end terminating in end flaps. The end flaps respectively connect to the walls through fold lines, and are foldable along the fold lines to close the tubular body at the ends.
When the walls are folded, the adjacent end flaps meet at corners which are extensions of the corner lines of the rectangular, tubular body, with the corners of the end flaps being slit down to the fold lines. Thus, in the prior art, the respective end flaps can be folded together in the typical manner of a cereal box, for closing the container at both ends.
However, particularly in the field of cereal boxes and other foods, this common structure results in the creation of a tiny aperture adjacent each junction of the fold lines of adjacent end flaps. It has been found that, particularly in tropical climates and while camping, small insects and the like are capable of gaining entry to the container through this corner aperture at the junction between the fold lines of two flaps and a fold line between two of the walls that define the rectangular, tubular body.
By this invention, an integral corner seal can be provided to rectangular cardboard boxes that are made from a cardboard piece or blank without the addition of added parts. The seal can be provided to a wide variety of cardboard box designs without the added expense of an extra part, and only with the minimal capital expense pertaining to a modification of the machine that does the scoring of the box.